docs: def matches_querytime(instance, querytime):
          """
          Checks whether the given instance satisfies the given QueryTime object.
  
          :param instance: an instance of Versionable
          :param querytime: QueryTime value to check against
          """
          if not querytime.active:
              return True
  
          if not querytime.time:
              return instance.version_end_date is None
  
          return (instance.version_start_date <= querytime.time and
                  (instance.version_end_date is None or
                   instance.version_end_date > querytime.time))